1. Field of the Invention
The present invention relates to an oil or fat (hereafter referred to as xe2x80x9coilxe2x80x9d merely) composition which effectively develops physiological functions derived from xcfx893 type unsaturated fatty acids having at least 20 carbon atoms, such as inhibition of platelet aggregation, and is excellent in effect of facilitating combustion of body fat, oxidation stability, flowability, flavor and the like, and oral medicinal compositions and foods comprising such an oil composition.
2. Description of the Background
In recent years, it has been clarified that diglycerides have an obesity-preventing effect, an effect to prevent an increase in weight, etc. (Japanese Patent Application Laid-Open Nos. 300828/1992, etc.), and it is attempted to incorporate these into various kinds of foods. It has been reported that when a glyceride mixture containing diglycerides at a high concentration is used in an oil phase, an edible oil-in-water type emulsion composition have a rich fatty feel and is good in flavor even when a fat content is decreased (Japanese Patent No. 2848849)
On the other hand, it has been known that xcfx893 type unsaturated fatty acids having at least 20 carbon atoms, such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are mainly contained in the form of triglyceride in fish oil and the like in plenty and have effective physiological activities such as anti-platelet aggregation property, antitumor activity, immune activation, antiallergic activity, improvement in brain function and improvement in visual function.
As oils highly containing such diglycerides and xcfx893 type unsaturated fatty acids, there have been known, for example, a natural oil that DHA among constitutive fatty acids of the oil is contained in a proportion of at least 60%, and the total content of diglycerides and monoglycerides is at least 80% of the oil (Japanese Patent Application Laid-Open No. 60181/1996), and the like.
However, the xcfx893 type unsaturated fatty acids having at least 20 carbon atoms are very poor in oxidation stability. When a xcfx893 type unsaturated fatty acid is oxidized, the oxidized unsaturated fatty acid involves a problem that not only its physiological activity functions are lost, but also the living body is adversely affected when such an unsaturated fatty acid is taken. In addition, an oil highly containing such a xcfx893 type unsaturated fatty acid has an unpleasant flavor derived from its raw oil, and so a problem is offered when it is used in food in particular. Further, xcfx893 type unsaturated fatty acids involve a problem that when they are converted into their corresponding diglycerides, the viscosity of the resulting diglycerides becomes high, so that the physiological activities of the xcfx893 type unsaturated fatty acids are hard to be developed.
It is therefore an object of the present invention to provide an oil composition which is good in flowability, hard to be oxidized and excellent in flavor, effectively develops physiological activities of xcfx893 type unsaturated fatty acids having at least 20 carbon atoms, and is excellent in effect of facilitating combustion of body fat, and oral medicinal compositions and foods comprising such an oil composition.
The present inventors have attracted attention to the compositions of acyl groups constituting a diglyceride and found that when a xcfx893 type unsaturated acyl group having at least 20 carbon atom and a monoenoic acyl group as acyl groups constituting a diglyceride are contained in specified amounts in an oil composition comprising a triglycerides, diglyceride, monoglyceride and free fatty acid in specified proportions, an oil composition which is hard to be oxidized, good in flowability and excellent in flavor, effectively develops physiological activities of xcfx893 type unsaturated fatty acids, and is excellent in effect of facilitating combustion of body fat is provided.
The present invention provides an oil composition comprising 0.1 to 59.8% by weight (hereafter indicated merely by xe2x80x9c%xe2x80x9d of a triglyceride, 40 to 99.7% of a diglyceride, 0.1 to 10% of a monoglyceride and at most 5% of a free fatty acid, wherein contents of xcfx893 type unsaturated acyl groups having at least 20 carbon atoms and monoenoic acyl groups in acyl groups constituting the diglyceride are 15 to 89.5% and 10 to 84.5%, respectively.
The present invention also provides an oral medicinal composition comprising such an oil composition.
The present invention further provides a food comprising such an oil composition.
In the present invention, no particular limitation is imposed on the number of carbon atoms in acyl groups constituting the triglyceride. However, the number of carbon atoms is preferably 8 to 24, particularly 16 to 22. The content of unsaturated acyl groups is preferably at least 55%, more preferably at least 70%, particularly preferably at least 90% based on all the acyl groups in the triglyceride. The triglyceride can be obtained from a vegetable oil such as soybean oil, rapeseed oil, palm oil, rice oil or corn oil, an animal oil such as beef tallow or fish oil, or a hardened oil, fractionated oil or random transesterified oil thereof. The content of the triglyceride in the oil composition according to the present invention must be 0.1 to 59.8%, preferably 5 to 55%. When the content of the triglyceride is 0.1 to 59.8%, and the content of the monoglyceride is 0.1 to 10%, unpleasant flavor derived from the free fatty acid and raw oil can be masked to improve the flavor of the resulting oil composition and also the oxidation stability thereof.
In the present invention, the acyl groups constituting the diglyceride include xcfx893 unsaturated acyl groups having at least 20 carbon atoms in a proportion of 15 to 89.5% preferably 20 to 70%, particularly preferably 25 to 65%, most preferably 50 to 65% based on all the acyl groups in the diglyceride and monoenoic acyl groups in a proportion of 10 to 84.5%, preferably 12 to 45%, particularly preferably 12 to 35%, most preferably 14 to 25%. The term xe2x80x9cxcfx893 type unsaturated acyl groupxe2x80x9d as used herein means an acyl group that a first unsaturated bond is located on the third carbon atom from a xcfx89 position when the positions of unsaturated bonds are specified from the xcfx89 position, and that has at least 2 unsaturated bonds. As the xcfx893 type unsaturated acyl groups having at least 20 carbon atoms, are preferred eicosapentaenoyl and docosahexaenoyl groups. The monoenoic acyl group is an acyl group having a carbonxe2x80x94carbon double bond. As examples thereof, are preferred hexadecamonoenoyl, octadecamonoenoyl, eicosamonoenoyl and docosamonoenoyl groups.
In the present invention, the acyl groups constituting the diglyceride preferably include xcfx896 type unsaturated acyl groups. The term xe2x80x9cxcfx896 type unsaturated acyl groupxe2x80x9d as used herein means an acyl group that a first unsaturated bond is located on the sixth carbon atom from a xcfx89 position when the positions of unsaturated bonds are specified from the xcfx89 position, and that has at least 2 unsaturated bonds. When the xcfx896 type unsaturated acyl groups are contained, development of drug intoxication such as hemolysis and hemorrhage, which are caused by excess ingestion of the xcfx893 type unsaturated acyl groups, can be inhibited and development of the physiological activities of the xcfx896 type unsaturated acyl groups can be facilitated. Examples of the xcfx896 type unsaturated acyl groups include a linoleyl group (cis,cis-9,12-octadecadienoyl group), a xcex3-linolenyl group (all cis-6,9,12-octadecatrienoyl group) and an arachidonyl group (all cis-5,8,11,14-eicosatetraenoyl group), with the linoleyl group being preferred. The content of the xcfx896 type unsaturated acyl groups in all the acyl groups in the diglyceride is preferably 0.5 to 75%, more preferably 0.5 to 50%, particularly preferably 1 to 25%, most preferably 1 to 15% in order to more remarkably develop the above-described effects of the present invention.
The diglyceride can be obtained by an optional process such as transesterification of any of various oils such as fish oil and rapeseed oil containing xcfx893 type unsaturated acyl groups, monoenoic acyl groups, xcfx896 type unsaturated acyl groups, etc. with glycerol or esterification of a fatty acid derived from such an oil with glycerol. Among these processes, the former process is particularly preferred. The reaction method thereof may be either a chemical reaction method making use of an alkali catalyst such as sodium methoxide, or the like or a biochemical reaction method making use of a lipolytic enzyme such as lipase. The content of such a diglyceride in the oil composition according to the present invention must be 40 to 99.7%, preferably 50 to 95%, particularly preferably 60 to 90%. When the content is 40 to 99.7%, the development of the physiological activities derived from the xcfx893 type unsaturated fatty acids is facilitated, and the effect of facilitating combustion of body fat becomes excellent.
In the present invention, a glyceride polymer may preferably be contained in order to more improve the oxidation stability. The glyceride polymer is a polymer obtained by intermolecular polymerization of a glyceride such as a triglycerides diglyceride or monoglyceride (for example, xe2x80x9cKagaku to Seibutu (Chemistry and Organism), Vol. 21, page 179, 1983), and no particular limitation is imposed on the polymerization degree of the glyceride, the positions of fatty acid esters, the kinds of acyl groups constituting the fatty acid esters, etc. The content of the glyceride polymer in the oil composition is preferably 0.1 to 10%, more preferably 0.1 to 5%, particularly preferably 0.2 to 2% from the viewpoints of improvement in oxidation stability of the oil composition and flavor. The amount of such a glyceride polymer can be controlled by suitably controlling reaction temperature conditions and the like upon synthesis of the glyceride polymer. The glyceride polymer can be determined by an HPLC process in which a gel permeation chromatographic column is connected.
The content of the monoglyceride in the oil composition according to the present invention must be 0.1 to 10%, preferably 0.1 to 5% from the viewpoint of improvement in the flavor of the oil composition. The content of free fatty acids must be at most 5%, preferably at most 2% from the viewpoint of improvement in the flavor of the oil composition.
The oil composition according to the present invention can be prepared by mixing the above-described components and suitably subjecting the resulting mixture to heating, stirring and/or the like. Alternatively, the oil composition according to tho present invention can be obtained by fractionating triglycerides, diglycerides, monoglycerides, glyceride polymers, free fatty acids and the like obtained by transesterification of an oil containing xcfx893 type unsaturated acyl groups, xcfx896 type unsaturated acyl groups, monoenoic acyl groups and the like, such as fish oil or rapeseed oils with glycerol, and then suitably mixing these fractionation products with one another. The oil composition according to the present invention can also be obtained by subjecting the reaction product obtained according to the above-described preparation process of the diglyceride to ordinary purification treatments such as molecular distillation, deodorizing and decolorizing.
The oil composition thus obtained has excellent physiological activities such as effects of facilitating combustion of body fat, reducing blood sugar value, consuming triglyceride in blood, reducing insulin in blood, improving liver function, reducing blood pressure, and inhibiting activation of plasminogen in addition to inhibitory effect on platelet aggregation, is good in digestibility because it is excellent in flowability, can be stored over a long period of time because it is excellent in oxidation stability, and moreover is excellent in flavor. In particular, since the xcfx893 type unsaturated acyl groups having at least 20 carbon atoms are present as acyl groups constituting the diglyceride, the oil composition acts at a lower concentration than the case where they are present as free fatty acids, and so it has good fast-acting property, and is good in flavor and safe. Since the oil composition according to the present invention has such excellent properties, it can be utilized for oral medicinal compositions and foods.
No particular limitation is imposed on the forms of the oral medicinal compositions, and examples thereof include solid preparations such as powder preparations, granule preparations, capsule preparations, pill preparations and tablet preparations; and liquid preparations such as aqueous preparations, suspension preparations and emulsion preparations. Such an oral preparation can be prepared by adding an excipient, a disintegrant, a binder, a lubricants a surfactant, an alcohols water, a water-soluble polymer, an sweet flavor, a taste corrigent, an acid flavor and/or the like commonly used according to the form of the oral preparation in addition to the oil composition in accordance with a method known per se in the art. Examples of oral medicinal compositions include platelet aggregation inhibitors, body weight-reducing agents, brain function improvers, visual function improvers and diabetes improvers. It is preferred that the amount of the oil composition according to the present invention to be incorporated in the oral medicinal composition be generally 0.1 to 100%, particularly 1 to 80% though it varies according to the application and form of the oral medicinal composition. The oral medicinal composition is preferably administered in a dose of 0.1 to 50 g per day in terms of the oil composition. Meanwhile, the administration may be once per day, or may be divided into several times per day.
With respect to the foods, the oil composition may be used as oil-containing foods containing the oil composition as a part of food. Examples of such oil-containing foods include healthy foods that the specified functions are exhibited to promote health. Specific examples thereof include tablet preparations, granule preparations, dressings such as French dressing, mayonnaises, creams, bakery foods such as bread and cookie, confectionery such as chocolates and potato chips, and drinks, in which such an oil composition is incorporated. Such oil-containing food can be produced by adding food materials commonly used according to the kind of the oil-containing food in addition to the oil composition in accordance with a method known per se in the art. It is preferred that the amount of the oil composition according to the present invention to be incorporated in food be generally 0.1 to 100%, particularly 1 to 80% though it varies according to the kind of the food. It may also be used as a food material of oils for fried foods such as tempura and fries, or oils for frizzled foods.